Obstacle detection system for an aerial work platform

ABSTRACT

A platform assembly includes a work platform including a platform floor and a safety rail extending from the platform floor to a rail height, and a primary sensor unit secured to the work platform and positioned adjacent one of the platform floor and the safety rail. The primary sensor unit is configured to monitor an area from the platform floor or from the safety rail to a space above the rail height and forward and aft of the work platform. The platform assembly enhances protection for an operator from sustained involuntary operation resulting in an impact with an obstruction or structure.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/904,682, filed Feb. 26, 2018, pending, which claims the benefit ofU.S. Provisional Patent Application Ser. No. 62/466,501, filed Mar. 3,2017, the entire contents of each of which are hereby incorporated byreference in this application.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

(NOT APPLICABLE)

BACKGROUND

The invention relates to work platforms and, more particularly, to awork platform including provisions to enhance protection for an operatorfrom sustained involuntary operation resulting in an impact with anobstruction or structure.

Aerial lifts with a work platform supported on an extendable boom havebeen fitted with sensor systems for preventing or minimizing the impactof overhead crush accidents. With an extendable boom, a safety hazardcan occur when an operator is positioned between the platform and astructure that may be located overhead or behind the operator, amongother places. A platform may be maneuvered into a position where theoperator is crushed between that structure and the platform, resultingin serious injury or death.

Scissor lifts are less susceptible to such safety hazards due to thenature of machine limitations to vertical movement of the platform. Anoverhead impact hazards still exists, however, and it would be desirableto provide a platform assembly that can detect potential obstacles andhazards with such a machine.

BRIEF SUMMARY

The platform assembly of the described embodiments may incorporate oneor more sensor units positioned on an exterior surface of the workplatform adjacent the platform floor. The sensors may be configured toprovide “fans” of coverage for detecting potential obstacles in avicinity of the platform. In some embodiments, extendable platforms areaccommodated by incorporating an additional sensor looking downward toprevent a potential crushing hazard on any objects/structures below theplatform extension in an extended position.

In an exemplary embodiment, a platform assembly includes a work platformincluding a platform floor and a safety rail extending from the platformfloor to a rail height, and a primary sensor unit secured to the workplatform and positioned adjacent the platform floor. The primary sensorunit is configured to monitor an area from the platform floor to a spaceabove the rail height and forward and aft of the work platform.

The primary sensor unit may also include two sensors facing insubstantially opposite directions, each of the sensors defining a fan ofcoverage. In this context, the sensors may be positioned relative toeach other such that the fans of coverage at least partially overlap. Insome embodiments, the two sensors may be oriented about 90° relative toeach other. The work platform may be rectangular shaped with two longsides and shorter front and back ends, and the primary sensor unit maybe positioned on at least one of the two long sides.

The work platform may also include a platform extension that may bedisplaceable between a retracted position and an extended position andthat extends the platform floor in at least one of a forward and arearward direction in the extended position. The platform assembly mayadditionally include a secondary sensor unit positioned adjacent theplatform extension and configured to monitor an area below the platformextension. In this context, the platform assembly may also include atarget panel positioned on the platform extension and displaceable withthe platform extension. The target panel may be in a sight line of thesecondary sensor in the extended position, and the target panel may beout of the sight line of the secondary sensor in the retracted position.

In another exemplary embodiment, a scissor lift includes a wheeledchassis, an arm stack supported on the wheeled chassis and displaceablebetween a raised orientation and a lowered orientation, and the platformassembly of the described embodiments supported on the arm stack anddisplaceable with the arm stack.

In yet another exemplary embodiment, a platform assembly includes a workplatform including a platform floor, two long sides, and a safety railextending from the platform floor to a rail height, and two primarysensor units secured to the work platform and positioned adjacent theplatform floor on each of the two long sides, respectively. The primarysensor units are configured to monitor an area from the platform floorto a space above the rail height and forward and aft of the workplatform. The primary sensor units each comprise two sensors facing insubstantially opposite directions, each of the sensors defining a fan ofcoverage.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects and advantages will be described in detail withreference to the accompanying drawings, in which:

FIGS. 1 and 2 show an exemplary platform assembly including a sensorunit;

FIG. 3 illustrates the fans of coverage by the sensor units; and

FIG. 4 shows a secondary sensor for the platform extension.

DETAILED DESCRIPTION

With reference to the drawings, the platform assembly according to thedescribed embodiments is shown with an exemplary application to ascissor lift. It will be appreciated that the platform assembly may beapplicable to other lift vehicle types, and the invention is notnecessarily meant to be limited to the exemplary scissor liftapplication shown and described.

The scissor lift shown in FIGS. 1-4 includes a wheeled chassis 12, anarm stack 14 supported on the wheel chassis 12 and displaceable betweena raised orientation and a lowered orientation, and a platform assembly16 supported on the arm stack via a platform base 18 that isdisplaceable with the arm stack 14.

The platform assembly 16 includes a work platform 20 with a platformfloor 22 and a safety rail 24 extending from the platform floor to arail height. The work platform 20 may also include a platform extension26 that is displaceable between a retracted position (FIG. 1) and anextended position (FIG. 3). The platform extension 26 extends theplatform in at least one of a forward and a rearward direction in theextended position. In some embodiments, the work platform 20 may includeplatform extensions 26 at both forward and aft ends. The platformextension 26 telescopes with complementary structure on the platform asis known.

The platform assembly 16 may also include a primary sensor unit 28secured to the work platform 20. As shown, the primary sensor unit 28may be positioned on an exterior surface of the work platform 20adjacent the platform floor 22. With a rectangular shaped platform 20including two long sides and shorter front and back ends, the primarysensor unit 28 may be positioned on one or both of the long sides.

In some embodiments, each of the primary sensor units 28 includes twosensors 30 facing in substantially opposite directions, where each ofthe sensors 30 defines a fan of coverage. The sensors 30 detect thepresence of a potential obstacle in the detection zone and output asignal to the machine control system. The sensors may use radar, LiDARor other suitable detection technology. A suitable sensor is theLeddarVu Vu8, available from LeddarTech in Quebec City, Canada.

The sensors 30 are secured within a sensor housing 32 that may beclamped to existing structure and can be positioned depending on theparticular application and targeted protection zone(s). The sensors 30in the housing 32 are oriented about 90° relative to each other.Relative to horizontal (or relative to the platform floor 22), aforward-facing sensor may be angled about 45° relative to horizontal,and a rearward-facing sensor may be angled about 135° (or 45° from theopposite direction) relative to horizontal.

It is desirable to position the sensors 30 in the housing 32 relative toeach other such that the fans of coverage at least partially overlap.FIG. 3 shows the overlapping fans of coverage 34. The coverage area mayfall between 90-110°. The fans are generally narrow (e.g., 2-5°), andwith the sensors 30 close to the platform floor 22, the sensors 30 alsocover the area above the platform while also looking forward and to therear of the machine. Specifically, the sensors are configured to monitoran area from the platform floor 22 to a space above the rail height andforward and aft of the work platform as shown in FIG. 3.

In the exemplary application shown in FIG. 3, the sensor units 28 arepositioned on both long sides of the platform in a generally centralposition relative to the platform with the platform extension 26 in itsextended position. To accommodate the platform extension 26, the sensorunits 28 are positioned slightly off center (i.e., forward or aft ofcenter) without the platform extension 26 adjacent the platform floor22.

With reference to FIG. 4, the platform assembly may also be providedwith a secondary sensor unit 36 positioned adjacent the platformextension 26 and configured to monitor an area below the platformextension 26. As shown, the secondary sensor 36 is fixed relative to theplatform extension 26 and may be mounted to the platform base 18. Thesecondary sensor 36 serves to prevent a potential crushing hazard on anyobjects/structures below the platform extension 26 in its extendedposition as shown.

A target panel 38 may be positioned on the platform extension 26 anddisplaceable with the platform extension 26. The target panel 38 is in asight line of the secondary sensor 36 with the platform extension 26 inits extended position, whereas the target panel 38 is out of the sightline of the secondary sensor 36 when the platform extension 26 is in theretracted position. The target panel 38 thus allows the sensor 36 toknow if the platform extension 26 is extended or retracted. Additionalsensors that are positioned and configured to monitor the area below theplatform can be utilized to detect objects that are close to the scissorlift (for example when working around sensitive objects like airplanes,glass walls, etc.) and to measure platform height.

In use, the driving components of the vehicle that are cooperable withthe lifting assembly for lifting and lowering the work platform arecontrolled by an operator input implement on a control panel and by adriving/control system communicating with the driving components and thecontrol panel. The control system also receives a signal from the sensorunit(s) 28 and controls operation of the driving components based onsignals from the operator input implement and the sensor unit(s) 28. Ata minimum, the control system is programmed to shut down drivingcomponents when the sensor units 28 detect an obstacle within thecoverage area. Alternatively, the control system may reverse the lastoperation when an obstacle is detected.

If function cutout is selected, when an obstacle is detected, the activefunction will be stopped immediately, and all non-active functions shallnot be activated. If a reversal function is selected, when an obstacleis detected during operation, the operation required RPM target ismaintained, and the active function only when an obstacle is detected isreversed until the reversal function is stopped. A ground horn and aplatform horn can be activated when the reversal function is active.After the reversal function is completed, engine RPM is set to low, andall functions are disabled until the functions are re-engaged forexample with a foot switch and operator controls. The system may includea sensor override button that is used to override the function cut outinitiated by the sensor units. If the override button is pressed andheld, it enables the lift functions if the foot switch and controls arere-engaged sequentially. In this event, function speed is set in creepmode speed automatically. The controller is programmed to avoid the cutout feature being disabled before the obstacle is detected regardless ofwhether the override button is pressed or released. This assures thatthe cut out feature will still be available if the override button isstuck or manipulated into an always-closed position.

The reversal function is implemented for various operating parameters ofthe machine. If a drive forward request is received when an obstacle isdetected, it is treated as a bump or obstacle in the road and will nottrigger the reversal function. Reversal function terminates based on thesensor signal, footswitch signal and time parameters that are set fordifferent functions, respectively. If the sensor signal changes fromobstacle-detected status to no-obstacle-detected status before themaximum reversal time is elapsed, then the reversal function will bestopped; otherwise, the reversal function is active until the maximumreversal time is elapsed.

Disengaging the footswitch also terminates the reversal function at anytime.

If an operator is trapped on the platform, ground control can beaccessed from the ground via a switch. In the ground control mode, ifthe platform switch is engaged, platform operation may be allowed increep speed. If the sensor units change status from obstacle to noobstacle, then operation is maintained in creep speed unless the groundenable and function control switch is re-engaged.

The platform assembly of the described embodiments incorporatesstrategically placed sensors for detecting potential obstacles andcrushing hazards. Although shown with an application to a scissor lift,the platform assembly is applicable to other work platforms and thelike. The platform assembly including the described sensor units servesto enhance protection for an operator from sustained involuntaryoperation resulting in an impact with an obstruction or structure.

While the invention has been described in connection with what ispresently considered to be the most practical and preferred embodiments,it is to be understood that the invention is not to be limited to thedisclosed embodiments, but on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

1. A platform assembly comprising: a work platform including a platformfloor and a safety rail extending from the platform floor to a railheight; and a primary sensor unit secured to the work platform andpositioned adjacent one of the platform floor and the safety rail, theprimary sensor unit being configured to monitor an area from theplatform floor or from the safety rail to a space above the rail heightand forward and aft of the work platform.